The UK version of the Seattle Angina Questionnaire (SAQ-UK): reliability, validity and responsiveness

The study assesses the reliability, validity and responsiveness of the UK version of the Seattle Angina Questionnaire (SAQ-UK). The instrument was anglicised and administered by self-completed postal questionnaire to 959 patients recruited from general practices in the North East of England. A total of 655 (68.3%) patients returned a completed questionnaire. Principal component analysis produced three important dimensions: physical limitations, anginal frequency and perception and treatment satisfaction. Four items that performed poorly were removed from the instrument. The removal of items greatly increased the number of computable scale scores. Estimates of internal reliability for the three dimensions ranged from 0.83-0.92. Estimates of test-retest reliability were above accepted standards. The correlation between the SAQ-UK scores and the SF-12, EuroQol and health transition was evidence for the validity of the instrument. The SAQ-UK produced responsiveness statistics that were comparable to the parent instrument and was more responsive to improvements in health than the generic instruments. The SAQ-UK is recommended as a measure of health outcome for the evaluation of angina management.